Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Arthropods and Echinoderms
Transcript
The Arthropods Chapter 33 General statistics Most numerous and successful phyla 400,000 known plant species 250,000 known non-arthropod animals Over 1,000,000 species of arthropods. 5 classes of arthropods General characteristics Arthropoda: From the Greek word arthron meaning “joint” and poda meaning “foot” 1) Jointed appendages used for crawling, swimming, flying, etc. More characteristics 2. Possess an exoskeleton • Made up of protein and chitin • Helps to waterproof and prevent water loss • Main disadvantage: exoskeleton does not “grow” with the organism. Must be shed. • molting 3. Segmented body 4. Well developed nervous systems 5. Open circulatory system Class Crustacea Lobsters, crayfish, crabs, shrimp. Mostly marine, some fresh water. All have 2 pairs of antennae on the head and 2 body regions. The crayfish Cephalothorax: fusion of the head and thorax Antennules: first pair of appendages attached to the head. Shorter of the two pairs of antennae Used for touch, taste, and balance More appendages 2nd pair : antennae (long) used for touch and tasting Mandibles (jaws) 1 pair. Used for crushing food Maxillae: 2 pairs. Used to handle food Maxillipeds: 3 pairs. Touch, taste, handling of food Chelipeds Large first legs where claws are found. Used for defense and grasping prey. and more appendages Walking legs (4 pairs) Swimmerets : appendages found on the underside of the abdomen. Used for swimming and carrying eggs and young. Internal Structure NUTRITION Food is caught with the chelipeds, crushed by the mandibles and passed into esophagus. Food then digested and wastes passed out the anus. Excretion Wastes from the blood are removed by the green glands in the head. Circulation and respiration Possess a dorsal heart. Open circulatory system (no capillaries nor veins) Arteries dump blood into open spaces, sternal sinus collects old blood and channels it to gills to pick up oxygen. Hemocyanin = copper containing pigment in the blood that aids in transport of oxygen. Gasses are exchanged at gills: Nervous system Well developed sensory organs Compound eyes, many sensory hairs Statocysts: sacs at the base of the antennules that aids in balance. Reproduction Separate sexes. Can determine sex by looking at first pair of swimmerets. Male will have enlarged first pair of swimmerets to transfer sperm to seminal receptacle of female during the fall. Eggs attach to swimmerets and hatch in the spring. Young stay attached until self sufficient. Baby crayfish: Class Chilopoda (centipedes) “centipede” literally means 100 feet Usually 30 to 60 legs, can be as many as 350 legs A distinct 6 segmented head Worm-like body with similar segments. More centipede facts All body segments have one pair of legs except the one behind the head and the last two. Fairly fast crawlers Feed on insects using poison claws. Usually found in dark damp places Under logs and rocks, in basements Class diplopoda (millipedes) Literally 1000 legs although no species has this many legs. World record is 750 legs. Usually anywhere from 100 to 300 legs. Two pairs of legs per body segment except for the last two segments. Slow moving No poison claws; feed on decaying plant material. Class arachnida Spiders, scorpions, ticks, and mites Mostly free-living. A few parasitic Some are harmful to humans (poisonous cause disease) Mostly helpful Get rid of pests like mosquitos Ticks Can cause disease ex. Spotted Rocky Mt. Fever Lyme Disease Lyme Disease Carried by deer ticks. Caused by a bacterium. Usually in wooded areas of Mid-Atlantic states and New England. spiders 1) 2) 2 body segments Cephalothorax (6 pairs of appendages) Adbdomen No antennae or Chewing jaws chelicerae First pair of appendages Also known as the “fangs” of a spider Will inject a poison into its prey. pedipalps Found between the first pair of legs and the chelicerae. Used for sensing chemicals and touch Used to manipulate food. Abdomen appendages: 4 pairs of walking legs Book lungs = respiratory organs on underside of abdomen Spinnerets: posterior end of abdomen, used to make silk for webs and raising and lowering themselves. Class insecta Most successful class of arthropods: 30 orders Live in all habitats High reproductive rates (all reproduce sexually) Small in size Only invertebrates capable of flight Why is flight such an advantage? Escape form enemies Search for food Allow insects to inhabit environments not inhabited by other organisms. Less competition for natural resources. 3 body regions: 1. 2. 3. Head (mouthparts, antennae, eyes) Thorax (3 pairs of legs, wings) Abdomen (respiratory structures) Specialized structures: Mouthparts 2 main types: legs Used for swimming, collecting pollen. Defense, grasping prey, jumping Incomplete metamorphosis Series of changes where an insect grows from eggs to a nymph to an adult Nymph = immature form that closely resembles the adult form except for certain features. Examples: grasshoppers, crickets Complete metamorphosis 4 stages: Eggs, larva, pupa, adult Larval stage examples: caterpillars, maggots Pupa: cocoon Changes are controlled by hormones. ex. Grasshopper (order Orthroptera) Head 2 large compound eyes 3 simple eyes 1 pair of antennae Mouthparts located outside the mouth(mandible, maxilla, special tonguelike organ) Thorax 3 separate segments to the thorax with each possessing a pair of legs Each leg has five segments ending in a clawed tarsus or foot 1st and 2nd pairs of legs are for crawling. Last pair used for jumping 2 pairs of wings Abdomen Made up of 10 segments Each segment has one pair of spiracles (openings into air tubes) 1 pair of tympanum (hearing organs) reproductive organs Female abdomen Ovipositor = hard four pointed organ at the base of the abdomen used to dig holes for burying eggs. Harmful effects of insects: Cause millions of dollars in crop damage. examples: Corn smut, rootworm, locusts, tent caterpillars Images: Transmit diseases Malaria = transmitted by mosquitoes West Nile virus = also mosquitoes West Nile link Destroy property Cockroaches termites moths Economic value of insects: Help pollinate fruit trees Produce honey Kill other harmful insects Eat dead plant and animal material Ways to kill insects: Most common: insecticides Trap and sterilize males Genetic engineering Bt corn Phylum Echinodermata Literally means “spiny-skinned” All marine Examples: characteristics Well developed coelom Endoskeleton Simplest organism showing embryological formation of the anus before formation of the mouth. Radial symmetry starfish Usually five arms but can possess up to 20 arms Extensive water-vascular system Water will enter through the sieve plate and pass through a series of canals into each arm. Tube feet Small water filled tubes or projections on the ventral surface used for locomotion, respiration, grabbing prey, and digestion. More starfish facts Feed on clams and oysters Skin gills = small finger-like appendages on the surface of starfish that is a site for respiration Separate sexes Can regenerate lost arms. An entire new starfish can grow as long as part of the central disk is present. Assignment: Page 730 1-17,20,21,22,25,26,27,30,32
